The Russian Navy operates seven
Project 667 BDRM "Delfin" class strategic missile submarines.
The submarines operate in the Northern Fleet and are based at the Saida
Guba Naval Base.

The submarines were built at the Severodvinsk Shipyard from 1981 to
1992. The first of class, K51, was commissioned in December 1985. In NATO
countries they are referred to as the "Delta IV" class
submarines.

The submarine design is similar to Project 667 BDR ("Delta
III" class). The submarine constitutes a double-hulled configuration
with missile silos housed in the inner hull.

The nose horizontal hydroplanes are arranged on the sail. They can
rotate to the vertical for breaking through the ice cover. The operational
diving depth of the submarine is 320 metres with a maximum depth of 400
metres. The propulsion system provides a run speed of 24 knots surfaced
and 24 knots submerged. The submarine carries supplies for an endurance of
80 days. The surface of the submarine has an acoustic coating to reduce
the acoustic signature.

The "Delfin" submarines are strategic nuclear missile
submarines designed to carry out strikes on military and industrial
installations and naval bases. The submarine carries the RSM-54 Makeyev's
construction bureaus missiles (NATO designation: SS-N-23 Skiff)
submarine-launched ballistic missile (SLBM). The RSM-54 is a three-stage
liquid-propellant ballistic missile with a range of 8,300 kilometers. The
warhead consists of four to ten multiple independently targeted re-entry
vehicles (MIRVs) each rated at 100 kT. The missile uses stellar inertial
guidance to provide a circle of equal probability (CEP) of 500 metres. The
CEP value is a measure of the accuracy of strike on the target and is the
radius of the circle within which half the strikes will impact.

The submarine is also capable of launching the Novator SS-N-15 Starfish
anti-ship missile or Mk 40 anti-ship torpedoes. Starfish is armed with a
200 kT nuclear warhead and has a range of up to 45 kilometres.

The submarine has four 533mm torpedo tubes capable of launching all
types of torpedoes, including antisubmarine torpedoes and antihydro-acoustic
devices. The system is fitted with a rapid reloading torpedo system. The
submarine can carry up to 18 missiles or torpedoes. All torpedoes are
accommodated in the bow section of the hull.

The submarines' radar warning receiver is the Brick Pulp system. The
optronic mast is the Brick Spit.

The Snoop Tray surface search radar operates at I-band.

The sonar suite includes the hull mounted Shark Gill sonar, which
operates at low and medium frequencies in active and passive search and
attack mode. The Mouse Roar active attack sonar is hull mounted and
operates at high frequency. The Shark Hide flank array sonar is a passive
low frequency system. A Pelamida towed array sonar provides a very low
frequency passive search capability. The dispenser for the thin line towed
array is visible on the after fin.

The submarine has two floating VLF and ELF antenna buoys to receive
radio messages, target designation data and satellite navigation signals
while remaining at a safe depth.

The "Delfin" is nuclear-powered with two VM-4 pressure water
reactors rated at 180 MW. There are two turbines, type GT3A-365 rated at
27.5 MW. The propulsion system drives two shafts with seven bladed fixed
pitch propellers.